1. Field of the Invention
This invention relates in general to obstetric devices, and more particular to devices useful in removing the fetus during vaginal delivery.
2. Prior Art
Today's state of the art obstetrics utilizes various procedures to assist in instances of difficult vaginal deliveries. These procedures basically fall into three categories: version, Caesarian and forceps assisted delivery. In the case of severe cephalo-pelvic disproportion, placenta previa, vaso previa, and other contraindications to vaginal delivery, the "C-Section," whether classic or low transverse, remains the mainstay procedure. However, it has long been recognized that to the extent that C-Section deliveries can be successfully avoided, statistical maternal and fetal benefits will be realized. Even the non-difficult vaginal delivery can benefit from non-traumatic assists.
Many problems may develop during delivery which require assistance from the attending obstetrician to successfully remove the baby from the birth canal. One such problem results from the presenting part of the baby, usually its head, descending too slowly. This is particularly true in the case of the primigravida mother. Even with a completely dilated and effaced cervix, and an adequate pelvis, a fetus might refuse to descend beyond station "+1", especially when the mother is suffering from contraction exhaustion. This can remain a problem even with an assist from administration of oxytocin (Pitocin). This problem is frequently exacerbated by anesthesia, particularly in the instance of epidural anesthesia which frequently produces induced non-beneficial partial atony of the engaged and dedicated muscles. Such partial atony frequently results in non-beneficial, and sometimes hazardous, prolongation of labor. Station "+1" is considered mid-pelvis and in the usual case is considered too high for a forceps assisted delivery. The risks to the fetus with forceps application at this level are extreme. Forceps cannot be safely used until the presenting part is at least at station "+2", and preferably between stations "+2" and "+3", which is the floor of the perineum.
Modern obstetrics has not developed an alternative to the use of forceps when an assisted natural delivery is indicated, such as when the fetus is consistently exhibiting late decelerations of heartbeat following contractions or is exhibiting non-variability of the baseline heartbeat rate. Obstetrical forceps are typically, in their various types, two-bladed instruments which are blindly inserted one blade at a time in a hopefully temporal-cheek position and then articulated together before assisting traction is applied. Actual traction is exerted slightly below or underneath the mandible. Traction applied with forceps is point concentrated and slippage of the forceps is increased because of natural lubrication, refusal of the fetal skull to conform to existing forceps design, and other known myriad of variables that vary from one fetus-to-pelvis physical relationship to another.
Even proper positioning of the forceps can result in harm to the fetus. For example, in instances of minimal cephalo-pelvic disproportion, the insertion of one blade of the forceps can exacerbate any slight deficiency in birth canal adequacy. In addition the softness, or pliability, of the fetal skull, coupled with the existence of sutures which separate the plates of the skull, render the skull susceptible to trauma associated with metal forceps assisted deliveries.
The problems associated with forceps assisted deliveries are well known, and many attempts have been made to improve forceps design. Examples of the current state of the art in forceps design can be seen in the following patents: U.S. Pat. No. 3,550,595 entitled "Obstetrical Forceps" and issued on Dec. 29, 1970 to Leonard E. Laufe; U.S. Pat. No. 3,605,748 entitled "Obstetrical Forceps" and issued on Sep. 20, 1971 to Hector Salinas-Benavides; U.S. Pat. No. 3,665,925 entitled "Obstetrical Forceps" and issued on May 30, 1972 to Hamo M. Dersookian; U.S. Pat. No. 3,785,381 entitled "Pressure Sensing Obstetrical Forceps" and issued on Jan. 15, 1974 to Brenton R. Lower et al; U.S. Pat. No. 3,789,849 entitled "Obstetrical Forceps" and issued on Feb. 5, 1974 to Leonard E. Laufe et al; and U.S. Pat. No. 3,794,044 entitled "Delivery Forceps" and issued on Feb. 26, 1974 to William O. Vennard.
Despite the long felt need and the large amount of time and effort spent to develop an alternative to forceps, the only assisting device developed which has seen some application is a vacuum extractor. Because the vacuum extractor presents its own set of clinical problems and risks, its use is limited and it has not served to supplant the use of forceps.